A very solid tile improvement; together with the Monastery (Armagh's Suzerainty tile improvement), the Cahokia Mounds are one of the only two improvements in the game that grant 1 Housing per improvement right from the get-go yet have no placement restriction. Either one can eradicate every Housing issues you may have, if you have access to one of them. However, the Cahokia Mounds are even stronger than the Monastery since their other bonuses (Gold, Amenity, Food) have much wider scope of applicability than Faith granted by the Monastery. A fantastic improvement that grants all the essentials to an early empire, the Cahokia Mounds should be the reason why you should definitely devote your Envoy power into Cahokia, the earlier the better. Beware, since Housing, Gold, Amenity and Food are what everyone needs, the competition for Cahokia's Suzerainty will be tough, especially when you do not spawn right next to it.

North American civilizations like the Adena, Hopewell, and Mississipian cultures constructed thousands—perhaps tens of thousands—of earthen mounds over the continent in the centuries before European contact. The purpose of many of these mounds remains mysterious. Some, but not all align with astronomical landmarks. But the greatest of these are the ones associated with the culture at Cahokia.

The largest mound at Cahokia is called “Monks Mound” because a community of Trappist monks built a settlement on or near it in the early colonial era. What the Cahokian citizens called it is unknown to us. The largest part of the structure is about 900 feet long, 250 feet wide, and approximately 20 feet tall, and is cleverly engineered to minimize the shrinkage and swelling associated with the clay soil, which accounts for why it has survived for centuries in an area prone to flooding. Monks Mound was enlarged and expanded over time, but eventually damaged in an earthquake in the time preceding the abandonment of the city.

Because the culture at Cahokia did not leave written records or inscription, little information about the purpose of the great mounds has survived. Archaeological evidence from the site suggests the mounds were a key part of the religious practices of the culture.